Device and method for nodal multiple access into communications channels

1. A method for multiple access to a communications channel on a satellite comprising the steps of:

transmitting a first modulated signal from a first site to a transponder;

receiving, from the transponder, a composite signal, the composite signal comprising the first modulated signal and a second modulated signal transmitted from at least a second site;

modulating the information bit stream with a modulating signal according to a frequency of a carrier of the received composite signal, comprising the steps of:

converting said composite signal into in-phase (I) and quadrature (Q) components of the second modulated signal defining a local I/Q coordinate space for signal processing at the first site, wherein said local I/Q coordinate space is determined with respect to a local oscillator reference and the carrier of the received composite signal;

determining an location for the I and Q components of the modulated information bit stream according to a distance between signals in said composite signal and a local signal; and

modulating the information bit stream according to the optimum I/Q location and the carrier;

transmitting the modulated information bit stream.

2. A method transmitting an information bit stream, comprising:

transmitting a first modulated signal from a first site to a transponder;

receiving, from the transponder, a composite signal, the composite signal comprising the first modulated signal and a second modulation signal transmitted from at least a second site;

modulating the information bit stream with a modulating signal according to a frequency of a carrier of the received composite signal; and

transmitting the modulated information bit stream.

3. The method of claim 2 , wherein modulating the information bit stream with the modulating signal according to the carrier of the received composite signal comprises:

removing local modulation from the received composite signal according to the carrier of the received composite signal; and

generating a modified modulated information bit stream at least in part from the received composite signal having the removed local modulation.

4. The method of claim 3 , wherein the frequency of the carrier of the received composite signal is determined at least part from a difference of the modified modulated information bit stream and the received composite signal.

5. The method of claim 3 , wherein the modified modulated information bit stream is generated based at least in part on a relative motion between the transponder and the first site.

6. The method of claim 5 , wherein the modified modulated information bit stream is modified based at least in part upon an estimate of a carrier frequency shift of the received composite signal.

7. The method of claim 5 , wherein the estimate of the carrier frequency shift of the received composite signal is determined at least in part according to a time-rate-of-change of a position of the transponder.

8. The method of claim 5 , wherein the modified modulated information bit stream is modified based at least in part upon a delay time between the transmission of the first modulated signal and the receiving of the composite signal having the first modulated signal.

9. The method of claim 8 , wherein the delay time is estimated at least in part according to a distance between a position of the transponder.

10. The method of claim 9 , wherein the transponder is disposed on a satellite in an orbit having orbital parameters and the position of the transponder is determined at least in part from the orbital parameters.

11. The method of claim 2 , wherein the modulated information bit stream is transmitted from the first site.

12. An apparatus for transmitting an information bit stream, comprising:

a transmitter, disposed at a first site, for transmitting a first modulated signal to a transponder; and

a receiver, disposed at the first site, for receiving, from the transponder, a composite signal, the composite signal comprising the first modulated signal and a second modulation signal transmitted from at least a second site;

wherein the transmitter further modulates the information bit stream with a modulating signal according to a frequency of a carrier of the received composite signal and transmits the modulated information bit stream.

13. The apparatus of claim 12 , wherein the transmitter modulates the information bit stream with the modulating signal according to the carrier of the received composite signal by:

removing local modulation from the received composite signal; and

generating a modified modulated information bit stream.

14. The apparatus of claim 12 , wherein the frequency of the carrier of the received composite signal is determined at least part from a difference of the modified modulated information bit stream and the received composite signal.

15. The apparatus of claim 12 , wherein the modified modulated information bit stream is generated based at least in part on a relative motion between the transponder and the first site.

16. The apparatus of claim 15 , wherein the modified modulated information bit stream is modified based at least in part upon an estimate of a carrier frequency shift of the received composite signal.

17. The apparatus of claim 15 , wherein the estimate of the carrier frequency shift of the received composite signal is determined at least in part according to a time-rate-of-change of a position of the transponder.

18. The apparatus of claim 15 , wherein the modified modulated information bit stream is modified based at least in part upon a delay time between the transmission of the first modulated signal and the receiving of the composite signal having the first modulated signal.

19. The apparatus of claim 18 , wherein the delay time is estimated at least in part according to a distance between a position of the transponder.

20. The apparatus of claim 19 , wherein the transponder is disposed on a satellite in an orbit having orbital parameters and the position of the transponder is determined at least in part from the orbital parameters.

21. The apparatus of claim 12 , wherein the modulated information bit stream is transmitted from the first site.